Find out all combinations without repeating the first elements - JAVA

Question

I've defined the next ArrayList:

ArrayList<ArrayList<String>> Elements

When I fill it up it goes like this:

[[AAA, AAG], [GAA, GAG], [GUA, GUC, GUG, GUU], [UUC, UUU], [GAA, GAG], [CCA, CCC, CCG, CCU], [CAC, CAU], [UAC, UAU], [UAC, UAU]]

I need to generate all possible combinations, starting always with the first position elements of the array, which in this case are: [AAA, AAG].

fi:

AAAGAAGUAUUCGAACCACACUACUAC

AAAGAAGUAUUCGAACCACACUACUAU

AAAGAAGUAUUCGAACCACACUAUUAC

Answer 1

Is there any reason why:

1) Set aside the first elements of your array.

2) Generate all combinations of the remainder of your array.

3) Add back the first elements to each combination.

Does not solve your problem?